U.S. Pat. No. 4,353,329 and No. 4,462,338 describe self-feeders for livestock having a base receptacle and a hopper positioned above it. The hopper, which contains the feed, has an aperture to allow feed to flow out of it into the base receptacle. A feed wheel mounted below the aperture includes an upper sweep portion extending up into the hopper and a lower portion including radially extending spokes located between the bottom wall of the hopper and the base receptacle. The spokes include upright paddles at their distal ends. In the embodiment shown in U.S. Pat. No. 4,462,338, an inverted moveable cone is provided above the sweep inside the hopper to control the rate of feed flow through the aperture into the base receptacle.
Such self feeders operate when an animal, such as a hog, pushes on one of the paddles to rotate the wheel. The rotating wheel rotates the sweep portion and feed falls from the hopper into the base receptacle, where it can be consumed by the animals. Such feeders are intended to lower feed waste by limiting the amount of feed in the base receptacle at any one time while still allowing the animals to access the feed at will by movement of the feed wheel.
Feeders of this type are used to feed from 25 to 90 pigs, depending on the size of the feeder and the size of the pigs. The animals take turns at the feeder, and it is important that feed always be available.
The animals do not instinctively know how to operate the feeder, so they must learn how to use it. To train pigs to use the feeder, it is customary to manually fill the feed trough (i.e. the base receptacle) and manually keep feed in the trough until the animals learn to associate movement of the feed wheel with the appearance of feed. If the animals fail to learn to operate the feeder, the result is hungry animals who overwhelm the feeder all at once with a behavior of emptying the trough and then simply waiting until feed re-appears through human intervention.
Often it is desirable to place such a feeder in a fence line in between two groups of animals which are kept separately. While such an arrangement can be quite efficient, since one feeder is serving two groups of animals, the feed consumption of the two groups must be relatively equal in both groups or excess feed may accumulate on one side of the feeder. This occurs because pigs tend to learn to move the paddles back and forth through a limited arc, thus failing to rotate feed in the base receptacle around the feeder. At its worse, accumulation of feed on one side of such a fence line feeder can actually jam movement of the feeder. If this occurs, human intervention is required to correct the situation. Manual turning of the feed wheel will sweep the excess feed to the hungrier group of animals in a single rotation.
However, the time spent on training the animals through manual feeding and the management time spent on balancing feed consumption could usefully be spent on other activities if these concerns could be addressed.